The development of modern roll milling

About 20 years ago the imminent death of the three roll mill was being forecast by many authorities. Their arguments were good. For the previous 50 years the technology of the three roll mill was virtually unchanged and the new sand mills, high speed dissolvers etc, were opening a new dimension to pigment dispersion. It was this that caused roll mill manufacturers, who, up until that time had concentrated on bettering the engineering aspects of their mills to consider how they could improve their customers' products in the various fields of paint, ink, soap, cosmetic and chocolate dispersing. A new era dawned for three roll mills, instead of simply improving their old mills the manufacturers hired dispersion experts. Chemists and technicians from the ink, chocolate and other industries joined the mill manufacturers and it very soon became apparent that many improvements could be made, so much so that leading mill manufacturers set up complete research laboratories separated into the various industries involved. Improvements rapidly followed. One of the first was static hydraulic pressure in place of the mechanical screw system. This soon gave way, on the more expensive mills, to dynamic hydraulic pressure. The difference being that in the latter system a pump is continually operating to maintain a constant pressure on the hydraulic oil and thereby on the rolls. And so was born a three roll mill which for the first time did not need constant re‐adjustment to maintain steady pressure regardless of the temperature when working.